update for required content

doc/copies.mdwn

@@ -30,3 +30,6 @@ refuse to do so.
 
 With N=2, in order to drop the file content from Laptop, it would need access
 to both USB and Server.
+
+For more complicated requirements about which repositories contain which
+content, see [[required_content]].

doc/internals.mdwn

@@ -150,6 +150,13 @@ Files matching the expression are preferred to be retained in the
 repository, while files not matching it are preferred to be stored
 somewhere else.
 
+## `required-content.log`
+
+Used to indicate which repositories are required to contain which file
+contents.
+
+File format is identical to preferred-content.log.
+
 ## `group-preferred-content.log`
 
 Contains standard preferred content settings for groups. (Overriding or

doc/preferred_content.mdwn

@@ -1,7 +1,7 @@
 git-annex tries to ensure that the configured number of [[copies]] of your
 data always exist, and leaves it up to you to use commands like `git annex
 get` and `git annex drop` to move the content to the repositories you want
-to contain it. But sometimes, it can be good to have more fine-grained
+to contain it. But often, it can be good to have more fine-grained
 control over which content is wanted by which repositories. Configuring
 this allows the git-annex assistant as well as 
 `git annex get --auto`, `git annex drop --auto`, `git annex sync --content`,